;
((doc) => {
  let curIdx = 0;

  const oMenuList = doc.querySelector('.menu-list'),
    oMenuItems = oMenuList.querySelectorAll('.menu-item');

  const init = () => {
    bindEvent();
  }

  function bindEvent() {
    oMenuList.addEventListener('click', handleMenuClick, false);
  }

  function handleMenuClick(e) {
    const tar = e.target,
      tagName = tar.tagName.toLowerCase();

    tagName === 'a' && menuChange(tar);
  }

  //切换菜单
  function menuChange(target) {
    const curParent = target.parentNode;
    oMenuItems[curIdx].className = 'menu-item';
    curIdx = [].indexOf.call(oMenuItems, curParent);
    curParent.className += ' active';
  }

  init();
})(document);